Hydroxylamine Promoted In Situ Growth of Fe₂O₃/Ni₃N Nanospikes on a Ni Surface for an Effective Hydrogen Evolution Reaction

Synthesizing bimetallic heterostructures of different shapes and sizes in nanodimensions is important to develop active catalysts for sustainable electrochemical splitting of water. Especially, facile synthetic strategies to access different nonmetallic dopant-based bimetallic heterostructures are limited in the literature. Herewith, a facile strategy involving NH 2 OH-mediated growth of NiFe 2 O 4 nanoflakes on Ni foam (NF) followed by the in situ synthesis of Fe 2 O 3 /Ni 3 N nanospike (average width of ≈14 nm) heterostructures is developed. The derivation of Fe 2 O 3 /Ni 3 N from the corresponding bimetallic ferrite intermediate possibly enabled the effective interfacing necessary for improved charge-transfer efficiency and enhanced catalytic activity. The resulting NF-Fe 2 O 3 /Ni 3 N-n electrodes have displayed effective hydrogen evolution reaction (HER) activity in alkaline solution in both pure and seawater electrolytes. The HER current density value of 10 mA/cm 2 ( j 10 ) is realized at low overpotential (η) values of 0.05 and 0.09 V in pure and seawater electrolytes, respectively, supporting the above. Along with the activity, NF-Fe 2 O 3 /Ni 3 N-n also exhibited extended durability of up to 60 h in seawater, supporting its viability for future commercial implementation.